1. Field
Embodiments described herein generally relate to methods for operating a gasifier. More particularly, such embodiments relate to transitioning a gasifier from an initial or starting state to a hydrocarbon feedstock processing or gasification state.
2. Description of the Related Art
Gasification is a high-temperature process usually conducted at elevated pressure to convert carbon-containing materials into carbon monoxide and hydrogen gas. Since this gas is often used for the synthesis of chemicals or synthetic hydrocarbon fuels, the gas is often referred to as “synthesis gas” or “syngas.”
Typical feeds to gasification include petroleum-based materials that are neat or residues of processing materials, such as heavy crude oil, coals, bitumen recovered from tar sands, kerogen from oil shale, coke, and other high-sulfur and/or high metal-containing residues; gases; and various carbonaceous waste materials. Dry or slurried hydrocarbon feedstocks are reacted in the gasifier in a reducing (oxygen-starved) atmosphere at high temperature and (usually) high pressure. The resulting syngas typically contains about 85 percent of the feed carbon content as carbon monoxide, with the balance being a mixture of carbon dioxide and methane.
In order to start the gasifier, a separate start-up burner is used to combust a start-up fuel to produce a combustion gas that is introduced to the gasifier in order to heat the gasifier up to gasification temperatures. Conventional start-up burners are complicated to operate, large, and expensive to construct.
There is a need, therefore, for improved systems and methods for transitioning a gasifier from an initial or starting state to a hydrocarbon feedstock processing state.